Refactor test for creating a new account with 0 balance (USD) (pass)

src/main/kotlin/camilyed/github/io/currencyexchangeapi/application/AccountService.kt

@@ -2,19 +2,20 @@ package camilyed.github.io.currencyexchangeapi.application
 
 import camilyed.github.io.currencyexchangeapi.domain.Account
 import camilyed.github.io.currencyexchangeapi.domain.AccountRepository
+import camilyed.github.io.currencyexchangeapi.domain.AccountSnapshot
 import java.math.BigDecimal
 
 class AccountService(
     private val repository: AccountRepository
 ) {
 
-    fun create(command: CreateAccountCommand): Account {
+    fun create(command: CreateAccountCommand): AccountSnapshot {
         val id = repository.nextAccountId()
         return Account(
             id = id,
             owner = command.owner,
             balancePln = command.initialBalance,
             balanceUsd = BigDecimal.ZERO
-        )
+        ).toSnapshot()
     }
 }

src/main/kotlin/camilyed/github/io/currencyexchangeapi/domain/Account.kt

@@ -1,16 +1,33 @@
 package camilyed.github.io.currencyexchangeapi.domain
 
 import java.math.BigDecimal
-import java.util.UUID
+import java.util.*
 
-data class Account(
-    val id: UUID,
-    val owner: String,
-    val balancePln: BigDecimal,
-    val balanceUsd: BigDecimal
+class Account(
+    private val id: UUID,
+    private val owner: String,
+    private var balancePln: BigDecimal,
+    private var balanceUsd: BigDecimal = BigDecimal.ZERO
 ) {
 
     init {
         require(balancePln >= BigDecimal.ZERO) { "Initial balance cannot be negative" }
+        require(balanceUsd == BigDecimal.ZERO) { "USD balance must start at 0" }
+    }
+
+    fun toSnapshot(): AccountSnapshot {
+        return AccountSnapshot(
+            id = id,
+            owner = owner,
+            balancePln = balancePln,
+            balanceUsd = balanceUsd
+        )
     }
 }
+
+data class AccountSnapshot(
+    val id: UUID,
+    val owner: String,
+    val balancePln: BigDecimal,
+    val balanceUsd: BigDecimal
+)

src/test/kotlin/camilyed/github/io/currencyexchangeapi/application/AccountServiceTest.kt

@@ -1,11 +1,11 @@
 package camilyed.github.io.currencyexchangeapi.application
 
-import camilyed.github.io.currencyexchangeapi.domain.Account
+import camilyed.github.io.currencyexchangeapi.domain.AccountSnapshot
 import camilyed.github.io.currencyexchangeapi.testing.ability.SetNextAccountIdAbility
 import camilyed.github.io.currencyexchangeapi.testing.ability.SetNextAccountIdAbility.Companion.accountRepository
+import camilyed.github.io.currencyexchangeapi.testing.assertions.hasBalanceInPln
 import camilyed.github.io.currencyexchangeapi.testing.assertions.hasBalanceInUsd
 import camilyed.github.io.currencyexchangeapi.testing.assertions.hasId
-import camilyed.github.io.currencyexchangeapi.testing.assertions.hasBalanceInPln
 import camilyed.github.io.currencyexchangeapi.testing.assertions.hasOwner
 import camilyed.github.io.currencyexchangeapi.testing.builders.CreateAccountCommandBuilder
 import camilyed.github.io.currencyexchangeapi.testing.builders.CreateAccountCommandBuilder.Companion.anAccount
@@ -66,7 +66,7 @@ class AccountServiceTest : SetNextAccountIdAbility {
             .hasBalanceInUsd(0.0)
     }
 
-    private fun create(command: CreateAccountCommandBuilder): Account {
+    private fun create(command: CreateAccountCommandBuilder): AccountSnapshot {
         return accountService.create(command.build())
     }
 }

src/test/kotlin/camilyed/github/io/currencyexchangeapi/testing/assertions/AccountAssertions.kt

@@ -1,32 +1,33 @@
 package camilyed.github.io.currencyexchangeapi.testing.assertions
 
 import camilyed.github.io.currencyexchangeapi.domain.Account
+import camilyed.github.io.currencyexchangeapi.domain.AccountSnapshot
 import strikt.api.Assertion
 import java.math.BigDecimal
 import java.util.*
 
-fun Assertion.Builder<Account>.hasId(expectedId: String) =
+fun Assertion.Builder<AccountSnapshot>.hasId(expectedId: String) =
     assert("has id $expectedId") {
         if (it.id == UUID.fromString(expectedId)) pass() else fail(
             description = "in fact it is %s",
             actual = it.id
         )
     }
 
-fun Assertion.Builder<Account>.hasOwner(expectedOwner: String) =
+fun Assertion.Builder<AccountSnapshot>.hasOwner(expectedOwner: String) =
     assert("has owner $expectedOwner") {
         if (it.owner == expectedOwner) pass() else fail()
     }
 
-fun Assertion.Builder<Account>.hasBalanceInPln(expectedBalance: Double) =
+fun Assertion.Builder<AccountSnapshot>.hasBalanceInPln(expectedBalance: Double) =
     assert("has initial balance $expectedBalance") {
         if (it.balancePln == BigDecimal(expectedBalance)) pass() else fail(
             description = "in fact it is %s",
             actual = it.balancePln
         )
     }
 
-fun Assertion.Builder<Account>.hasBalanceInUsd(expectedBalance: Double) =
+fun Assertion.Builder<AccountSnapshot>.hasBalanceInUsd(expectedBalance: Double) =
     assert("has balance in usd $expectedBalance") {
         if (it.balanceUsd == BigDecimal(expectedBalance)) pass() else fail(
             description = "in fact it is %s",